Multilayer Capacitor Electrode Design for Acoustic Noise Suppression
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Solution Overview
Problem
Multilayer capacitors generate acoustic noise due to vibration, which is transmitted to substrates via solder, causing structural complications and noise amplification.
Innovation Solution
A multilayer capacitor design with external electrodes that extend from end faces to principal and side faces, featuring a metallic layer structure with an intermetallic compound layer exposed at ridge portions, allowing solder to adhere only to the lower surfaces, reducing vibration transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the multilayer capacitor is mounted on the substrate via solder, then electrical connection is achieved, but vibration is transmitted to the substrate causing acoustic noise
Solution Approach 1:
The invention extracts the harmful vibration transmission path by removing solder from the end face portions of the external electrodes. The solder is allowed to adhere only to the lower surfaces of the external electrodes, excluding the end face portions, thereby separating the electrical connection function from the vibration transmission path.
Solution Approach 2:
The invention applies different solder adhesion properties to different regions of the external electrodes. The lower surfaces have solder adhesion while the end face portions are designed to be solder-free, creating local quality differences that achieve both electrical connection and vibration suppression.
2Object-generated harmful factors
If external terminals are added to separate the multilayer capacitor main body from the substrate, then vibration transmission is reduced, but structural complexity increases
Solution Approach 1:
The invention merges the external electrodes with the functions of both electrical connection and vibration suppression. The external electrodes simultaneously serve as electrical terminals and as vibration isolation elements, eliminating the need for separate external terminals and simplifying the overall structure.
Solution Approach 2:
The external electrodes are designed to perform multiple functions: providing electrical connection through solder adhesion on lower surfaces, suppressing vibration transmission by excluding solder from end face portions, and maintaining mechanical stability. This multi-functionality eliminates the need for additional components.
3Reliability
If solder is applied to the end faces of external electrodes, then electrical connection is improved, but vibration transmission to substrate increases
Solution Approach 1:
The invention segments the external electrode surface into distinct regions with different solder adhesion properties: lower surfaces that accept solder for electrical connection, and end face portions that remain solder-free to suppress vibration transmission. This spatial segmentation resolves the contradiction between connection and vibration suppression.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design effectively suppresses acoustic noise by preventing solder fillet formation on the external electrodes, thereby minimizing vibration transmission to the substrate, enhancing noise suppression and preventing structural issues like the tombstone phenomenon.
Implementation Method 1
When an AC voltage is applied to such a multilayer capacitor, distortion occurs in the dielectric layer due to an electrostrictive effect of the ceramic material, and the multilayer capacitor in itself vibrates. The vibration of the multilayer capacitor is transmitted to a substrate mounting the multilayer capacitor via solder or other means.
Implementation Method 2
the multilayer capacitor is mounted on the substrate via solder, the substrate becomes deformed due to the vibration of the multilayer capacitor transmitted thereto through the solder adherent to the pair of external electrodes
Data Source
AI summary
A multilayer capacitor includes a pair of external electrodes each having an end face portion; a first principal face extending portion; a second principal face extending portion; a first side face extending portion; and a second side face extending portion. The pair of external electrodes each includes a base electrode and a metallic layer. The metallic layer includes a first metallic layer and a second metallic layer located outside the first metallic layer. An intermetallic compound layer is located outside the first metallic layer, and is exposed from the second metallic layer in a ridge portion lying between the end face portion and the first principal face extending portion, a ridge portion lying between the first side face extending portion and the first principal face extending portion, and a ridge portion lying between the second side face extending portion and the first principal face extending portion.